Puffy is key at rest breaks to keep you from chilling down too much. You might want to consider the ski jacket as a layer. Better yet you can rent a puffy from http://www.whittakermountaineering.com/pg/home which is better than buying if you don't need it on a regular basis. I've used them several times. Cheers!

sneakyracer wrote:1 single layer PolarMax crew long underwear top (100% Acclimate Polyester, cheap and effective)1 double layer PolarMax crew long underwear top (100% Acclimate Polyester, cheap and effective, a bit thicker but stil thing, tight fitting and strechy)1 Marmot Men's Power Stretch Full Zip Jacket (looks nice, might use it alone or over a poly t shirt or over the polarmax's, most likely will spend a lot of time with this garment on as outermost layer)1 Outdoor Research Credo Softshell Jacket (if it gets colder / snowy and or windy this goes on)1 Marmot Mica Jacket (for rain/sleet or extra wind/snow protection, very very light, saved me space in my bag)1 fleece jacket (for use at higher camps and maybe as a midlayer if it gets really cold)

I would leave out one of the insulation jackets. I can't imagine you would be wearing all these layers at the same time.

I'd only take one of the MH pants, I couldn't see wearing both at the same time. I'd only have one layer of the PolarMax for the same reason. The insulated pants will be too hot to use for climbing. Maybe if you are idle or descending, but the other insulation should be okay.

sneakyracer wrote:1 3L insulated camelbak reservoir

The camelbak hose will freeze if the temperature gets below freezing, even if the hose is insulated.

jspeigl wrote:The camelbak hose will freeze if the temperature gets below freezing, even if the hose is insulated.

Not necessarily. If you blow the water back into the bladder each time after you drink it won't freeze. The thing is, I find it hard to remember to do that .

True, I for one love camelbaks BUT for some reason I always drink less water when I carry one and its tough to keep track of how much water is left obviously.

I am considering getting a Mountain Hardwear Phantom down jacket or a Marmot Guide Down Sweater... Its either that or use the ski jacket as my "puffy" warm jacket for breaks. The down jackets mentioned are much lighter and pack much smaller which is a plus. In my experience what gets me is the wind. Between the shell and softshell there is enough wind protection I believe.I have not been higher than 13k feet but I read that at higher altitudes one tends to get cold more easily given equal temperatures than at lower altitudes.

I am confident that on Iztaccihuatl I wont need a puffy jacket, on Orizaba with its very large ice and snow fields and even higher altitudes, I probably will.

I want to be as safe as posible. If I dont summit so be it. I want to enjoy the mountain. I want to spend a few days on Iztaccihuatl so Orizaba might not even happen. Dont know for sure yet.

jspeigl wrote:The camelbak hose will freeze if the temperature gets below freezing, even if the hose is insulated.

Not necessarily. If you blow the water back into the bladder each time after you drink it won't freeze. The thing is, I find it hard to remember to do that .

True, I for one love camelbaks BUT for some reason I always drink less water when I carry one and its tough to keep track of how much water is left obviously.

I am considering getting a Mountain Hardwear Phantom down jacket or a Marmot Guide Down Sweater... Its either that or use the ski jacket as my "puffy" warm jacket for breaks. The down jackets mentioned are much lighter and pack much smaller which is a plus. In my experience what gets me is the wind. Between the shell and softshell there is enough wind protection I believe.I have not been higher than 13k feet but I read that at higher altitudes one tends to get cold more easily given equal temperatures than at lower altitudes.

I am confident that on Iztaccihuatl I wont need a puffy jacket, on Orizaba with its very large ice and snow fields and even higher altitudes, I probably will.

I want to be as safe as posible. If I dont summit so be it. I want to enjoy the mountain. I want to spend a few days on Iztaccihuatl so Orizaba might not even happen. Dont know for sure yet.

I've had camelbacks freeze even when I have blown the water back. I will never use a camelback in cold weather. Just not worth the risk.
The down jackets you mention would be ideal. A shell should block the wind fine, but I climbed the last 2,000 feet or so of Orizaba wearing my down jacket. You will be happy to have it.